1. Field of Invention
This invention relates to a liquid crystal display. More particularly, this invention relates to a high brightness liquid crystal display.
2. Description of Related Art
Optoelectronics technologies have recently progressed by leaps and bounds due to the coming of the digital era, which also has stimulated the market for liquid crystal displays (LCDs). LCD has many advantages, such as high display quality, small volume, light weight, low driving voltage and low power consumption. Hence, LCDs are widely used in small portable televisions, mobile telephones, notebook computers, desktop monitors, projector televisions and the like, and have gradually replaced the conventional cathode ray tube (CRT) displays as a mainstream display unit.
Because liquid crystal isn't luminescent itself, a backlight module is used as a light source so that an image on LCD can be displayed. The backlight type LCD comprises a front-end liquid crystal panel and a back-end backlight module.
Brightness of is one of important properties of LCD. Conventionally, the method for improving the brightness of the LCD is to increase aperture ratio or to use optical films, such as brightness enhance film, in the backlight module. However, if the aperture ratio is increased to improve the brightness of the LCD, difficulties of manufacturing process and costs are raised. If several optical films were used in the backlight module to improve the brightness, another problem would be generated. For example, light is absorbed by the optical films during light transmission, which results in decreased utilization of light and increased costs. Furthermore, damage of the optical films can be caused by performing reliability tests of these optical films, which results in increased costs. In addition, if these optical films are disposed improperly, a moire effect, which is an interference pattern, are easily generated, so defects in visual effect are likely to happen.
Thus, in the U.S. Pat. No. 6,421,105, it provides a method to solve these problems, which micro lens arrays having curved surfaces are formed on an upper glass substrate surface of a LCD cell. The curved surfaces of the micro lens arrays are used to improve the brightness of the LCD. However, it is not easy to manufacture micro-scale devices having curved surfaces. Moreover, due to the restriction of sizes and structures of the micro lens, increasing the curve degree of the curved surfaces of the micro lens cannot enhance the brightness of the LCD further.